Cardiovascular Journal of Africa: Vol 27 No 1 (January/February 2016)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 1, January/February 2016

AFRICA

(other abnormalities generally presenting much earlier).

Congenital heart and vascular defects that have been described

include dextrocardia with situs inversus totalis (mirror image),

situs solitus with normal relationship of great arteries (variation

of dextroversion), situs solitus with levo- and/or dextro-

transposition of the great arteries, and dextrocardia associated

with polysplenia syndrome.

Dextrocardia can also be associated with the heterotaxy

syndromes of asplenia and polysplenia. Of the two syndromes,

polysplenia is more likely to be associated with less severe cardiac

malformations and therefore more likely to be encountered

in adults. Up to 50% of cases of polysplenia syndrome can

have dextrocardia. In polysplenia syndrome, there tends to be

non-cyanotic congenital heart defects.

Abnormalities associated with polysplenia syndrome are

bilaterally symmetrical liver, bilateral bi-lobed lungs with bilateral

hypo-arterial bronchi (left isomerism), bilateral superior vena

cava, absence of the intrahepatic portion (interruption) of the

inferior vena cava with azygous or hemi-azygous continuation,

common atrium with complete absence of the atrial septum,

endocardial cushion defect, hypoplasia or absence of one

ventricle, valvular or subvalvular pulmonary stenosis, aortic

stenosis or atresia, and double-outlet right ventricle. There

is also an unexplained relationship between polysplenia and

Kartagener’s syndrome.

Left ventricular non-compaction (LVNC) is a hereditary

primarycardiomyopathywithcharacteristicfeaturesof prominent

trabeculations and conspicuous inter-trabecular recesses that

penetrate deeply into the left ventricular myocardium, with a

thin, compacted ventricular free wall (mainly in the affected

areas), and diffuse systolic dysfunction with hypokinesia.

The

majority of reported cases describe involvement of the left

ventricle, but the right ventricle and septum can also be affected.

Non-compaction of the ventricular myocardium was first

described in 1932, in an autopsy on a newborn.

Since then, due

to increasing awareness and continuously improving technology,

the rates of diagnosis of LVNC have been steadily increasing.

Imaging studies are the cornerstone of diagnosis of LVNC, with

echocardiography being the main diagnostic tool. Computed

tomography, angiography and magnetic resonance imaging

(MRI) have been and can be used with equal success at

diagnosis of the entity as well as for identification of associated

abnormalities.

In the normally developed heart, the left ventricle has up to

three prominent trabeculations and is less trabeculated than the

right ventricle. In LVNC the trabeculations are more numerous

(left ventricle compared to right ventricle) and thicker with deep

recesses between the trabeculae.

Several diagnostic criteria have been proposed for LVNC,

including a ratio of two for the wall thickness between the

non-compacted trabeculated layer and the non-trabeculated

compacted layer of the LVNC at end-systole, as measured

along the parasternal short axis on echocardiography.

Other

criteria that can be used for diagnosis and possible classification

include:

(1) prominent and deep inter-trabecular recesses in the

left ventricular lateral wall and apex, (2) direct blood flow from

the ventricular cavity into the deep inter-trabecular recesses,

as assessed by Doppler echocardiography, (3) two-layered

structure of the ventricular wall, with an end-systolic ratio of

non-compacted-to-compacted layer exceeding 1.4 (in infants),

and (4) absence/presence of co-existing cardiac abnormalities.

The clinical presentation can vary and initially most children

and adults are asymptomatic. The left ventricular function then

gradually deteriorates and other presenting events may also

occur, such as cardiac failure and thromboembolic events. The

prognosis is poor, with patients facing the possibility of sudden

death (due to cardiac arrhythmias, ischaemic strokes, etc.) or

eventual death due to heart failure.

The systolic dysfunction is thought to occur due to a relative

ischaemia of the myocardium with a mismatch of myocardial

oxygen supply and demand.

Restricted myocardial perfusion

and decreased coronary flow reserve, which suggests a coronary

microcirculatory dysfunction, has been demonstrated previously

by Jenni

et al

. with positron emission tomography (PET)

Fig. 3.

Computed tomography angiogram (coronal slices) with lung window (A) and venous phases (B) and (C). Splenule (small

black arrow), bilateral hypo-arterial bronchi (black double arrowheads), interruption of the inferior vena cava (larger white

arrow) and azygous continuation of the inferior vena cava (small white arrows) are all part of the heterotaxy syndrome.